Lens test?

Mitchell

Any comments on my crude lens test would be appreciated.
I bought a used Nikkor 70-200mm, 2.8, VR lens on another forum.
This "legendary" piece of glass just seemed soft to me when I took a few quick shots. I decided to do a controlled test to see if it needs a repair.
Here are some staggered box shots with the lens focused on the center box. Straight out of the camera with no sharpening.

200mm @ f2.8


100% crop


Compared with my 180mm prime @ f2.8


100% crop

gluwater

Well I'm not a Nikon shooter but i have heard good things about this lens. My only suggestion to you is that this is an unfair test. Prime lenses will almost always yield superior results over Primes. I'm sure there are exceptions but generally this will be true. To me both shots look pretty similar. Other things you may want to check are, were you using a tripod, was your focus correct, did you try any other apertures? Some lenses are sharper at different apertures. Maybe retry your test using different apertures and find your lenses sweet spot and then decide if you think it is acceptable or not. Good luck!

HeldDown

Even though it's "legendary," remember it's 2.8, and it's a zoom. Both of those factors negatively effect sharpness. You can't compare a zoom to a prime, it's almost apples and oranges.

However, those look remarkably similar; if they were identical exposures, I doubt they'd be distinguishable. Be happy you've got a zooming, VR lens that's fast and compares to your fast prime!

EDIT: I was thinking to myself "I don't think I've ever noticed one of Mitchell's pics without his daughter in it, but I guess this IS just soup"... but then I saw her in the frame in the back, and all was well with the world

ziggy53

Mitch,

I would bet there is a minimum focus distance that is quite different between these two lenses. Typically, zooms need more minimum focus than primes need. Make sure you take that into consideration and don't perform critical tests right at the minimum either, give it an additional 10-15% distance over minimum, at least. Besides the sharp falloff at minimum, there is usually a more moderate falloff in performance just before minimum.

Zooms are more complicated beasts than primes and a good prime will beat a good zoom any day. The images you present look very similar to me, so I don't think there is a problem, at least not a gross problem.

My own testing would include very high contrast targets shot under high contrast circumstances. I would also test at infinity.

Finally, I test a prospective lens under actual. or close to actual, conditions I intend to use the lens. Especially with second-hand lenses, if I got a good price, I may still find use for the lens if it performs well under consistant and repeatable parameters. Knowing the limitations of equipment is always important and may be the most definitive measure of worthiness.

Best,

ziggy53

Mitchell

Ziggy, thanks for your reply. I was well beyond the minimal focus distance of both lenses. I think I'll try to replicate some of these tests with different apertures.

HeldDown, glad you noticed the theme of my daughters in all of my shots. I thought the addition of organic soup would get Andy drooling.

Mongrel

Hi Mitch,
Frankly looking at the crops I'd say you have a *very* good copy of that 70-200. In fact, on my monitor anyway, they look pretty much equal as far as sharpness goes with just a tad better contrast to the prime.

I'm not sure how much better it could be